com.diffplug.common.swt

Class SwtExec

java.lang.Object

java.util.concurrent.AbstractExecutorService

com.diffplug.common.swt.SwtExec

All Implemented Interfaces:

Rx.HasRxExecutor, Executor, ExecutorService, ScheduledExecutorService

Direct Known Subclasses:

SwtExec.Blocking

public class SwtExec
extends AbstractExecutorService
implements ScheduledExecutorService, Rx.HasRxExecutor

{link ExecutorService}s which execute on the SWT UI thread.

There are three "kinds" of SwtExec:

• async -> performs actions using Display.asyncExec(java.lang.Runnable)
• immediate -> performs actions immediately if called from a UI thread, otherwise delegates to Display.asyncExec(java.lang.Runnable).
• blocking -> performs actions immediately if called from a UI thread, else delegates to Display.syncExec(java.lang.Runnable).

In addition to the standard executor methods, each SwtExec also has a method guardOn(org.eclipse.swt.widgets.Widget), which returns a SwtExec.Guarded instance - the cure for "Widget is disposed" errors. Guarded has methods like SwtExec.Guarded.wrap(java.lang.Runnable) and SwtExec.Guarded.execute(java.lang.Runnable), whose contents are only executed if the guarded widget is not disposed.

SwtExec.Guarded also contains the full API of Rx, which allows subscribing to Observables and ListenableFutures while guarding on a given widget.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	SwtExec.Blocking An SwtExec (obtained via blocking()) which adds a blocking get() method.
static class	SwtExec.Guarded Executor and Rx for conducting actions which are guarded on an SWT widget.

Field Summary

Fields

Modifier and Type	Field and Description
protected Display	display
protected Rx.RxExecutor	rxExecutor
protected Scheduler	scheduler

Method Summary

Modifier and Type	Method and Description
static SwtExec	async() Returns an "async" SwtExecutor.
boolean	awaitTermination(long timeout, TimeUnit unit) Blocks until all tasks have completed execution after a shutdown request, or the timeout occurs, or the current thread is interrupted, whichever happens first.
static SwtExec.Blocking	blocking() Returns a "blocking" SwtExecutor.
void	execute(Runnable runnable) Executes the given command at some time in the future.
Rx.RxExecutor	getRxExecutor() Returns an instance of Rx.RxExecutor.
Scheduler	getRxScheduler() Returns a Scheduler appropriate for Rx.
SwtExec.Guarded	guardOn(ControlWrapper wrapper) Returns an API for performing actions which are guarded on the given ControlWrapper.
SwtExec.Guarded	guardOn(Widget widget) Returns an API for performing actions which are guarded on the given Widget.
static SwtExec	immediate() Returns an "immediate" SwtExecutor.
boolean	isShutdown() Returns true if this executor has been shut down.
boolean	isTerminated() Returns true if all tasks have completed following shut down.
<V> ScheduledFuture<V>	schedule(Callable<V> callable, long delay, TimeUnit unit) Creates and executes a ScheduledFuture that becomes enabled after the given delay.
ScheduledFuture<?>	schedule(Runnable command, long delay, TimeUnit unit) Creates and executes a one-shot action that becomes enabled after the given delay.
ScheduledFuture<?>	scheduleAtFixedRate(Runnable command, long initialDelay, long period, TimeUnit unit) Creates and executes a periodic action that becomes enabled first after the given initial delay, and subsequently with the given period; that is executions will commence after initialDelay then initialDelay+period, then initialDelay + 2 * period, and so on.
ScheduledFuture<?>	scheduleWithFixedDelay(Runnable command, long initialDelay, long delay, TimeUnit unit) Creates and executes a periodic action that becomes enabled first after the given initial delay, and subsequently with the given delay between the termination of one execution and the commencement of the next.
void	shutdown() Initiates an orderly shutdown in which previously submitted tasks are executed, but no new tasks will be accepted.
List<Runnable>	shutdownNow() Attempts to stop all actively executing tasks, halts the processing of waiting tasks, and returns a list of the tasks that were awaiting execution.
static void	timerExec(int ms, Runnable runnable) Executes the given runnable in the UI thread after the given delay.

Methods inherited from class java.util.concurrent.AbstractExecutorService

invokeAll, invokeAll, invokeAny, invokeAny, newTaskFor, newTaskFor, submit, submit, submit

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.util.concurrent.ExecutorService

invokeAll, invokeAll, invokeAny, invokeAny, submit, submit, submit

Field Detail

display

protected final Display display

scheduler

protected final Scheduler scheduler

rxExecutor

protected final Rx.RxExecutor rxExecutor

Method Detail

async

public static SwtExec async()

Returns an "async" SwtExecutor.

When execute(Runnable) is called, the Runnable will be passed to Display.asyncExec.

immediate

public static SwtExec immediate()

Returns an "immediate" SwtExecutor.

• When execute(Runnable) is called from the SWT thread, the Runnable will be executed immediately.
• Else, the Runnable will be passed to Display.asyncExec.

blocking

public static SwtExec.Blocking blocking()

Returns a "blocking" SwtExecutor.

• When execute(Runnable) is called from the SWT thread, the Runnable will be executed immediately.
• Else, the Runnable will be passed to Display.syncExec.

This instance also has a blocking get() method for doing a get in the UI thread.

timerExec

public static void timerExec(int ms,
                             Runnable runnable)

Executes the given runnable in the UI thread after the given delay.

guardOn

public SwtExec.Guarded guardOn(Widget widget)

Returns an API for performing actions which are guarded on the given Widget.

guardOn

public SwtExec.Guarded guardOn(ControlWrapper wrapper)

Returns an API for performing actions which are guarded on the given ControlWrapper.

getRxExecutor

public Rx.RxExecutor getRxExecutor()

Returns an instance of Rx.RxExecutor.

Specified by:

getRxExecutor in interface Rx.HasRxExecutor

getRxScheduler

public Scheduler getRxScheduler()

Returns a Scheduler appropriate for Rx.

execute

public void execute(Runnable runnable)

Executes the given command at some time in the future. The command may execute in a new thread, in a pooled thread, or in the calling thread, at the discretion of the Executor implementation.

Specified by:

execute in interface Executor

Parameters:

runnable - the runnable task

Throws:

RejectedExecutionException - if this task cannot be accepted for execution.

NullPointerException - if command is null

shutdown

public void shutdown()

Initiates an orderly shutdown in which previously submitted tasks are executed, but no new tasks will be accepted. Invocation has no additional effect if already shut down.

Specified by:

shutdown in interface ExecutorService

Throws:

SecurityException - if a security manager exists and shutting down this ExecutorService may manipulate threads that the caller is not permitted to modify because it does not hold RuntimePermission("modifyThread"), or the security manager's checkAccess method denies access.

shutdownNow

public List<Runnable> shutdownNow()

Attempts to stop all actively executing tasks, halts the processing of waiting tasks, and returns a list of the tasks that were awaiting execution.

There are no guarantees beyond best-effort attempts to stop processing actively executing tasks. For example, typical implementations will cancel via Thread.interrupt(), so any task that fails to respond to interrupts may never terminate.

Specified by:

shutdownNow in interface ExecutorService

Returns:

list of tasks that never commenced execution

Throws:

SecurityException - if a security manager exists and shutting down this ExecutorService may manipulate threads that the caller is not permitted to modify because it does not hold RuntimePermission("modifyThread"), or the security manager's checkAccess method denies access.

isShutdown

public boolean isShutdown()

Returns true if this executor has been shut down.

Specified by:

isShutdown in interface ExecutorService

Returns:

true if this executor has been shut down

isTerminated

public boolean isTerminated()

Returns true if all tasks have completed following shut down. Note that isTerminated is never true unless either shutdown or shutdownNow was called first.

Specified by:

isTerminated in interface ExecutorService

Returns:

true if all tasks have completed following shut down

awaitTermination

public boolean awaitTermination(long timeout,
                                TimeUnit unit)
                         throws InterruptedException

Blocks until all tasks have completed execution after a shutdown request, or the timeout occurs, or the current thread is interrupted, whichever happens first.

Specified by:

awaitTermination in interface ExecutorService

Parameters:

timeout - the maximum time to wait

unit - the time unit of the timeout argument

Returns:

true if this executor terminated and false if the timeout elapsed before termination

Throws:

InterruptedException - if interrupted while waiting

schedule

public ScheduledFuture<?> schedule(Runnable command,
                                   long delay,
                                   TimeUnit unit)

Creates and executes a one-shot action that becomes enabled after the given delay.

Specified by:

schedule in interface ScheduledExecutorService

Parameters:

command - the task to execute

delay - the time from now to delay execution

unit - the time unit of the delay parameter

Returns:

a ScheduledFuture representing pending completion of the task and whose get() method will return null upon completion

Throws:

RejectedExecutionException - if the task cannot be scheduled for execution

NullPointerException - if command is null

schedule

public <V> ScheduledFuture<V> schedule(Callable<V> callable,
                                       long delay,
                                       TimeUnit unit)

Creates and executes a ScheduledFuture that becomes enabled after the given delay.

Specified by:

schedule in interface ScheduledExecutorService

Parameters:

callable - the function to execute

delay - the time from now to delay execution

unit - the time unit of the delay parameter

Returns:

a ScheduledFuture that can be used to extract result or cancel

Throws:

RejectedExecutionException - if the task cannot be scheduled for execution

NullPointerException - if callable is null

scheduleAtFixedRate

public ScheduledFuture<?> scheduleAtFixedRate(Runnable command,
                                              long initialDelay,
                                              long period,
                                              TimeUnit unit)

Creates and executes a periodic action that becomes enabled first after the given initial delay, and subsequently with the given period; that is executions will commence after initialDelay then initialDelay+period, then initialDelay + 2 * period, and so on. If any execution of the task encounters an exception, subsequent executions are suppressed. Otherwise, the task will only terminate via cancellation or termination of the executor. If any execution of this task takes longer than its period, then subsequent executions may start late, but will not concurrently execute.

Specified by:

scheduleAtFixedRate in interface ScheduledExecutorService

Parameters:

command - the task to execute

initialDelay - the time to delay first execution

period - the period between successive executions

unit - the time unit of the initialDelay and period parameters

Returns:

a ScheduledFuture representing pending completion of the task, and whose get() method will throw an exception upon cancellation

Throws:

RejectedExecutionException - if the task cannot be scheduled for execution

NullPointerException - if command is null

IllegalArgumentException - if period less than or equal to zero

scheduleWithFixedDelay

public ScheduledFuture<?> scheduleWithFixedDelay(Runnable command,
                                                 long initialDelay,
                                                 long delay,
                                                 TimeUnit unit)

Creates and executes a periodic action that becomes enabled first after the given initial delay, and subsequently with the given delay between the termination of one execution and the commencement of the next. If any execution of the task encounters an exception, subsequent executions are suppressed. Otherwise, the task will only terminate via cancellation or termination of the executor.

Specified by:

scheduleWithFixedDelay in interface ScheduledExecutorService

Parameters:

command - the task to execute

initialDelay - the time to delay first execution

delay - the delay between the termination of one execution and the commencement of the next

unit - the time unit of the initialDelay and delay parameters

Returns:

a ScheduledFuture representing pending completion of the task, and whose get() method will throw an exception upon cancellation

Throws:

RejectedExecutionException - if the task cannot be scheduled for execution

NullPointerException - if command is null

IllegalArgumentException - if delay less than or equal to zero